README file for DARTE v1.0

This file describes the data fields and geographic projection of the Database for Road Transportation Emissions (DARTE) version 1.0
For a detailed description of the methodology by which DARTE was constructed, please refer to:

Gately CK, Hutyra LR, Sue Wing I, 2015, "Cities, traffic, and CO2: A multi-decadal assessment of trends, drivers, and scaling relationships"
Proc. Natl. Acad. Sci. Available at: www.pnas.org/content/early/2015/04/01/1421723112.full.pdf

The DARTE data files are available for download at http://dx.doi.org/10.7910/DVN/28999

The data repository contains:

1. 'DARTE_1km_co2.zip'

This is a compressed, comma-delimited file that reports annual carbon dioxide emissions from on-road vehicle activity in the coterminous United States
for the years 1980 through 2012, on a spatial grid with 1 kilometer resolution grid cells. The file can be uncompressed using the unix utiity gzip.

The column headers are as follows:

cellid (INTEGER)     = unique ID of 1km grid covering the coterminous U.S. The grid coordinate system is projected using the projection described below.
ddx (FLOAT)          = longitude of SW corner of grid cell in decimal degrees
ddy (FLOAT)          = latitude of SW corner of grid cell in decimal degrees
lon_meters (INTEGER) = longitude of SW corner of grid cell in meters
lat_meters (INTEGER) = latitude of SW corner of grid cell in meters
Mg_co2_YYYY (FLOAT)  = Megagrams (metric tons) of carbon dioxide emitted in year YYYY. The range of YYYY is 1980 through 2012.

2. 'DARTE.gdb.zip'

This a compressed ESRI file geodatabase. The geodatabase contains a single feature class of the DARTE 1km grid, including emissions for each year.

The column headers are the same as the CSV file above.

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GIS Projection of DARTE 1km grid
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DARTE emissions are assigned to cells in a 1 x 1 km grid.
The DARTE 1km grid cells nest exactly within the Vulcan Product�s 10km grid cells for ease of comparison and combination.

Extent
Top: 								1265000.000000 m
Right:			  					974000.000000 m
Left: 								2334000.000000 m
Bottom:								-303000.000000 m

Projection:							Lambert_Conformal_Conic
False_Easting:						0.00000000
False_Northing:						0.00000000
Central_Meridian:					-97.00000000
Standard_Parallel_1:				33.00000000
Standard_Parallel_2:				45.00000000
Scale_Factor:						1.00000000
Latitude_Of_Origin:					40.00000000
Linear Unit: 						Meter

Geographic Coordinate System:		GCS_WGS_1984
Datum: 					            D_WGS_1984
Prime Meridian: 			        Greenwich
Angular Unit: 				        Degree
